The present invention pertains to a rapid-action coupling with a safety lock for connecting fluid lines, in particular, fuel lines in the manufacture of automobiles. This rapid-action coupling includes of a tubular plug-in part with a circumferential holding rib, a coupling housing with a cylindrical receptacle cavity and a separate holding element. The holding element has elastically expandable holding edges that are radially directed into the receptacle cavity and engage behind the holding rib after the insertion of the plug-in part. A safety clip that can be positioned in front of the opening of the housing and is provided with a second locking mechanism in case the snap-in mechanism of the holding element fails.
A rapid-action coupling is shown in U.S. Pat. No. 5,069,424. The safety clip that is discussed in this publication (and referred to as a xe2x80x9credundant clipxe2x80x9d) encompasses the tubular plug-in part directly behind the holding rib by means of a clamp. The clip includes two inwardly bent fingers on the ends of two arms that outwardly extend around the opening in the housing. These fingers engage into a circumferential groove arranged on the outside of the housing body when the plug-in part has reached its completely engaged position in the receptacle cavity of the coupling housing. That is, the fingers engage when the snap-in fingers of the holding spring engage behind the holding rib after the insertion of the plug-in part. If the primary snap-in mechanism fails, for whatever reason, the plug-in part is still held by the safety clip, the clamp of which then presses against the holding rib. This safety clip not only provides a second locking mechanism, but simultaneously represents a visual indication for the secure locking of the plug-in part.
One disadvantage of this rapid-action coupling is that the safety clip needs to be manufactured from spring steel so as to be able to withstand the high retention forces occurring in the worst-case scenario. In order to ensure the proper function of the safety clip, it is also necessary to initially press the safety clip onto the pipe section situated in front of the holding rib and to insert the safety clip into the receptacle cavity together with the plug-in part. Both snap-in fingers need to be manually bent apart during this process such that the snap-in fingers are able to engage into the grooves when they are moved over the head of the coupling housing. This means that the assembly of the two parts is extremely complicated and requires skilled assembly personnel.
The present invention is based on the objective of designing a rapid-action coupling with a safety lock that can be positioned and fixed in front of the plug-in opening separately from the plug-in part. Also, the locking means can be easily moved into their locking position after the plug-in part is locked in the holding element.
According to the present invention, the safety clip includes a frame that is adapted to the end face of the coupling housing and can be locked on the corresponding outer projections of the coupling housing by means of two elastically expanding clips. The frame is connected to snap-in fingers that can be inserted into the receptacle cavity. The front ends of the fingers can be supported on the holding rib of the fully engaged plug-in part. Snap-in tabs that are directed toward the rear and outwardly protrude from the snap-in fingers simultaneously engage behind contact edges that inwardly protrude from the housing wall.
In some embodiments, the frame contains a support ring that is centrally arranged in the plane of the frame. The inside diameter of the support ring is slightly larger than the outside diameter of the plug-in part. The outside diameter of the support ring is identical to the outside diameter of the holding rib. The snap-in fingers are integrally formed onto the outer edge of the support rib in such a way that they are able to elastically expand diagonally outward opposite to the inserting direction. The snap-in fingers are automatically supported on the holding ring when the support ring is installed into the receptacle cavity and simultaneously engage behind the inwardly protruding contact edges. Consequently, when the plug-in part is inserted, the support ring may be simultaneously pulled into the receptacle cavity by the holding rib such that the locking elements are automatically moved into their locking position. A clip according to the present invention can be advantageously manufactured from a hard-elastic plastic material.
According to one preferred embodiment of the invention, one end of each of the snap-in fingers is integrally formed onto the outer edge of the support ring. The other ends of the snap-in fingers are flexibly connected to two opposing side walls of the frame via bridge webs that are integrally formed onto those ends in an approximately semicircular fashion. The snap-in fingers are respectively provided with one inwardly directed and one outwardly directed snap-in tab. The two inwardly directed snap-in tabs engage behind the holding rib after the insertion of the plug-in part. The two outwardly directed snap-in tabs are supported on the contact edges of the housing wall. The snap-in fingers are pulled outward by the spring force of the bridge webs if they are not properly engaged. In addition, the compressed bridge webs provide a visual indication for the proper function of the safety clip.
A conventional rapid-action plastic coupling has a holding element with opposing holding edges that are integrally formed onto support bodies. The support bodies are connected to pressure plates at their ends via resilient webs that converge in the shape of a V. The pressure plates protrude outward through corresponding openings in the housing wall such that they can be externally depressed in order to separate the coupling. The support bodies protrude into bays that are laterally recessed into the housing wall and yield into the bays when the pressure plates are depressed. In this type of plastic coupling, it is advantageous if the snap-in fingers have such a width that they can be inserted into and locked in the free space between the resilient webs, and if the outer snap-in tabs can be supported on the front edge of the opening underneath the pressure plates viewed in the inserting direction. This provides the advantage that the safety clip can be subsequently retrofitted into finished coupling housings. That is, the safety clip can be installed without requiring any additional modifications.